<template>
    <div class="app-container">
        <h2 style="text-align: center;">发布新课程</h2>
        <el-steps :active="1" process-status="wait" align-center style="marginbottom: 40px;">
            <el-step title="填写课程基本信息"/>
            <el-step title="创建课程大纲"/>
            <el-step title="提交审核"/>
        </el-steps>

        <el-form label-width="120px">
            <el-form-item label="课程标题">
                <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"></el-input> 
            </el-form-item>

            <!-- 所属分类 -->
            <el-form-item label="课程分類">
                <el-select
                    v-model="courseInfo.subjectParentId" placeholder="一級分類" @change="subjectLevelOneChanged">
                    <el-option
                        v-for="subject in subjectOneList"
                        :key="subject.id"
                        :label="subject.title"
                        :value="subject.id"/>
                </el-select>

                <!-- 二级分类 -->
                <el-select v-model="courseInfo.subjectId" placeholder="二級分類">
                    <el-option
                        v-for="subject in subjectTwoList"
                        :key="subject.id"
                        :label="subject.title"
                        :value="subject.id"/>
                </el-select>

            </el-form-item>

            <!-- 课程讲师 -->
            <el-form-item label="课程讲师">
                <el-select
                    v-model="courseInfo.teacherId"
                    placeholder="请选择">
                    <el-option
                        v-for="teacher in teacherList"
                        :key="teacher.id"
                        :label="teacher.name"
                        :value="teacher.id"/>
                </el-select>
            </el-form-item>

            <el-form-item label="总课时">
                <el-input-number :min="0" v-model="courseInfo.lessonNum" controls-position="right" placeholder="請填寫課程的縂課時"/>
            </el-form-item>

            <!-- 课程简介 -->
            <el-form-item label="课程簡介">
                <el-input v-model="courseInfo.description" placeholder=" "></el-input> 
            </el-form-item>

            <!-- 课程封面 -->
            <el-form-item label="课程封面">
                <el-upload
                    :show-file-list="false"
                    :on-success="handleAvatarSuccess"
                    :before-upload="beforeAvatarUpload"
                    :action="BASE_API+'/eduoss/fileoss'"
                    :class="avatar-uploader">
                    <img :src="courseInfo.cover">
                </el-upload>
            </el-form-item>

            <el-form-item label="课程价格">
                <el-input-number :min="0" v-model="courseInfo.price" controls-position="right" placeholder=""/>
            </el-form-item>

            <el-form-item>
                <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
            </el-form-item>
        </el-form>
    </div>
</template>
<script>
import * as course from '@/api/edu/course'
import * as subject from '@/api/edu/subject'

export default {
    data() {
        return{
            saveBtnDisabled:false,
            courseInfo:{
                title: '',
                subjectId: '',
                subjectParentId: '',
                teacherId: '',
                lessonNum: 0,
                description: '',
                cover: '/static/01.jpg',
                price: 0
            },
            courseId: '',
            BASE_API: process.env.VUE_APP_BASE_API,
            teacherList: [],
            subjectOneList: [],
            subjectTwoList: []
        }
    },
    created(){
        //獲取路由中的id值
        if(this.$route.params && this.$route.params.id){
            this.courseId = this.$route.params.id

            //根据id查询课程信息
            this.getInfo()
        } else {
            //初始化所有講師
            this.getListTeacher()
            //初始化一級分類
            this.getOnesubject()
        }
    },
    methods:{
        //根据id查询课程信息
        getInfo(){
            course.getCourseInfoId(this.courseId)
                .then(response => {
                    //在 courseInfo 课程信息中，包含了 一级分类id 和 二级分类id
                    this.courseInfo = response.data.courseInfoVo

                    //1 查询所有的分类 包过 一级分类和二级分类
                    subject.getSubjectList()
                        .then(response => {
                            //2 获取一级分类
                           this.subjectOneList = response.data.list

                           //3 把所有的一级分类数组进行遍历，
                           for (var i = 0; i < this.subjectOneList.length; i++) {
                                //获取一级分类
                                var element = this.subjectOneList[i]
                                //比较当前 course Info 里面的一级分类id和所有的二级分类id
                                if (this.courseInfo.subjectParentId == element.id) {
                                    //获取一级分类下的所有二级分类
                                    this.subjectTwoList = element.children
                                }
                           }
                        })
                        //初始化所有講師
                        this.getListTeacher()
                })
        },
        //上傳成功調用的方法
        handleAvatarSuccess(res,file){
            this.courseInfo.cover = res.data.url
        },
        //上傳之前調用的方法
        beforeAvatarUpload(file){
            const isJGP = file.type === 'image/jpeg'
            const isLt2M = file.size / 1024 / 1024 < 2
            if(!isJGP){
                this.$message.error('上傳頭像圖片只能是JGP格式')
            }
            if(!isLt2M){
                this.$message.error('上傳頭像圖片大小不能超過2MB')
            }
            return isJGP & isLt2M
        },
        //點擊一級分類，會觸發 change ，展示對於的二級分類
        subjectLevelOneChanged(value){
            //value 就是一級分類的id
            //alert(value)
            for(var i=0;i< this.subjectOneList.length;i++){
                var oneSubject = this.subjectOneList[i]
                if(value === oneSubject.id){
                    this.subjectTwoList = oneSubject.children
                    this.courseInfo.subjectId = ''
                }
            }
        },
        //查詢所有一級分類
        getOnesubject(){
            subject.getSubjectList()
                .then(response => {
                   this.subjectOneList = response.data.list
                })
        },
        //查詢所有老師
        getListTeacher(){
            course.getAllTeacher()
                .then(response => {
                   this.teacherList = response.data.items
                })
        },
        addCourse(){
            course.addCourseInfo(this.courseInfo)
                .then(response => {
                    //提示信息
                    this.$message({
                        type: 'success',
                        message: '添加課程信息成功!'
                    });
                    
                    //跳轉到第二步
                    this.$router.push({path:'/course/chapter/'+response.data.courseId})
                })
        },
        updateCourse(){
            course.updateCourseInfo(this.courseInfo)
                .then(response => {
                    //提示信息
                    this.$message({
                        type: 'success',
                        message: '修改課程信息成功!'
                    });
                    
                    //跳轉到第二步
                    this.$router.push({path:'/course/chapter/'+this.courseId})
                })
        },
        saveOrUpdate(){
            //判断是新增还是修改
            if (!this.courseInfo.id) {
                this.addCourse()
            }else{
                this.updateCourse()
            }
        }
        
    }

}
</script>
